Electronic printing apparatus



March 8, 1966 s. E. ENGELSTAD ETAL 3,238,921

ELECTRONIC PRINTING APPARATUS Filed March 14, 1963 5 Sheets-Sheet l 0mmmy G0R6 1 [#65]. $740 6/186??? FAELAA I Jon/v CLEYBERGH INVENTORS CJXYMMarch 1966 G. E. ENGELSTAD ETAL 3,238,921

ELECTRONIC PRINTING APPARATUS 5 Sheets-Sheet 2 Filed March 14, 1963GEORGE E. E/VGELSTAD GILBERT FAELLAC/ JOHN CLEYBERGH INVENTORS BY; I

Mamh 1966 G. E. ENGELSTAD ETAL 3,233,921

ELECTRONIC PRINT ING APPARATUS Filed March 14. 1963 5 Sheets-Sheet 5Games A. Emeasmo 6/155 FAELLAC/ JOHN ClEYBERl-l INVENTORS ATT'YS.

March 8, 1966 G. E. ENGELSTAD ETAL 3,233,921

ELECTRONIC PRINTING APPARATUS Filed March 14, 1963 5 Sheets-Sheet 4GEORGE Eueflsrno GILBERT HusuAc/ JOHN CLEYBERGH INVENTORS A'I'TYs.

March 1966 cs. E. ENGELSTAD ETAL ELECTRONIC PRINTING APPARATUS FiledMarch 14, 1965 United States Patent 3,238,921 ELECTRONIC PRINTINGAPPARATUS George E. Engelstad, Skokie, John Cleybergh, Des

Plaines, and Gilbert Faellaci, Niles, Ill., assignors to A. B. DickCompany, Chicago, 111., a corporation of Illinois Filed Mar. 14, 1963,Ser. No. 265,176 7 Claims. (Cl. 118637) This invention relates to anapparatus for use in the development of electrostatic images. Inparticular, the apparatus of this invention includes a fluid developingsystem which can be employed for developing the electrostatic images ona continuous or individual basis whereby increase in the efiiciency andeconomy of producing copy sheets can be realized.

Many systems have previously been employed for developing latent imagesdisposed on a carrier or copy sheet. In the xerox process, anelectrostatic image is formed on a selenium plate by exposure of thecharged plate to a light pattern. The electrostatic image on the plateis thereafter transferred to a copy sheet and the image is developedthrough the use of materials in a dry system composed of a pigment oftoner mixed with a situable dry carrier.

In a further system known as the Videograph process, an original isscanned to develop an electrostatic signal which is transferred to acathode ray tube having an array of conductive wires in its face. Theelectrostatic signal is then imposed on the wires to transmit anelectrostatic charge through the tube for deposition onto copy paperadvanced past the tube. The electrostatic image is then developed withthe use of a dry system similar to the system described above.

The use of a dry process for the development of an electrostatic imagehas been found to be subject to a number of objections. It has beenfound difiicult to achieve a desirable uniformity in the distribution ofthe toner and carrier particles in the developer with the result thatvariations occur in the intensity of color in the developed image.Background has also been found to be a problem due to the inability tocompletely remove the developing materials -from non-image areas of thecopy sheet. An additional drawback results due to the necessity forfixing .the developer on to the copy sheet as by means of a heatingoperation. A considerable amount of heat is required to fuse thecomponents in the toner and this heat has effected distillation of someingredients in the copy sheet which has resulted in condensation uponelements in the developing apparatus. The heat has also been known todamage the copy sheet as by charring. Finally, the fine powder employedin a dry system has been found to condensate the atmosphere as well asthe elements making up the developing apparatus.

It is an object of this invention to provide an apparatus for use in thedevelopment of electrostatic images on copy sheets which overcomes thedrawbacks recognized in developing systems employing dry techniques.

It is a more particular object of this invention to provide a developingapparatus which utilizes a liquid developing system wereby substantialimprovements in the economy and efficiency of a developing operation canbe realized.

These and other objects of this invention will appear hereinafter andfor purposes of illustration but not of limitation, specific embodimentsof this invention are shown in the accompanying drawings in which:

FIGURE 1 is a diagrammatic view of the developing apparatus of thisinvention;

FIGURE 2 is a detail elevational view of the mechanisms employed forapplying liquid developer to a copy sheet;

FIGURE 3 is a detail rear elevational view of a portion of the developerapplying means;

FIGURE 4 is a side elevational view of the developer applying means;

FIGURE 5 is a side elevational view taken on the opposite side of thedeveloper applying means;

FIGURE 6 is an elevational view partly in section of the dryingmechanism for the copy sheet;

FIGURE 7 is an enlarged cross-sectional view taken about the line 7-7 ofFIGURE 6; and

FIGURE 8 is an enlarged cross'sectional view taken about the line 88 ofFIGURE 6.

The developing apparatus of this invention comprises means which areadapted to support a sheet having a latent electrostatic image disposedthereon. The sheet is moved by its supporting means to a developingmeans and a source of liquid developer is supplied at this point. Thedeveloping means includes mechanisms which are effective to uniformlydistribute the developer over the surface of the sheet which holds thelatent image. The developer is thereafter dried on the sheet to producethe completed copy.

The means for applying the developer to the copy sheet represent animportant phase of the invention since uniformity in application isquite important. In addition, the preferred form of this inventionincludes a novel drying system which is effective to fix the image onthe copy sheet in a highly efiicient manner.

The diagrammatic illustration in FIGURE 1 provides a general descriptionof the operation of the apparatus of this invention. In this apparatus,.a paper tape 20 is fed from a supply roll 22 over a plurality of guiderollers 24 which extend throughout the apparatus. In the embodimentshown, the tape 20 is first fed to an electronic printing tube 36 of thetype employed in a Videograph system. After receiving a latentelectrostatic image, the tape is transferred to a liquid developingmeans 38. The liquid developer is uniformly distributed over the tape atthis time, and the tape is then fed to a dryer 40. A takeup roll 42 isadapted to receive the tape with a fixed image thereon in systemsinvolving a continuous developing operation. Although the illustratedembodiment provides for the use of a continuous paper tape, it will beunderstood that the mechanisms of this invention are equally suitablefor use in the developing of sheets of a variety of compositions andsizes.

FIGURES 2 through 5 illustrate in detail the structure of the liquiddeveloping means 38 of this invention. The developing means includes atray 44 through which liquid developer 46 is circulated. The developeris fed to the developing means through a line 48 and the outlet 4% ofthe tray 44 communicates with the line 50 whereby the developer can becirculated as by means of pump 52 (see FIGURE 1).

The inlet line 48 communicates with a cylindrical member 54 whichextends laterally across the tray 44. This cylindrical member includesan internal tube 55 which has openings 57 defined in its lower surface.An elongated slot 56 is defined by the cylindrical member 54, and thisslot extends along the length of the cylindrical member for a distanceat least sufficient for the distribution of liquid developer on allportions of the tape 20' which receive an electrostatic image. A roller58 is disposed opposite the slot 56 and the tape 20 is guided in contactwith the underside of this roller whereby the tape will continuouslymove past the slot 55. Roller 59 acts to squeeze some excess developerout of the tape prior to passage to the dryer.

In the operation of the apparatus, liquid developer is fed through line48 into the tube 55 whereby the developer passes out of the openings 57into the enclosure defined by the cylindrical member 54. The liquid isthen fed through the slot 56 into contact with the surface of the tapewhich carries the electrostatic image. It will be appreciated that theliquid issuing from the slot 56 will be in the form of a narrow band andsince the pump 52 will operate continuously, fresh developing liquidwill be continuously moved into contact with the surface of the movingtape. During circulation of the liquid developer, the ingredientsthereof which may be depleted can be re plenished so as to furtherenhance the uniform conditions of the operation.

It will be noted that the cylindrical member 54 has a hook meansassociated therewith adjacent the coupling 61 with the line 48. Thishook means is adapted to engage knob 62 which is threaded into amounting plate 64. When the knob 62 is loosened, the hook means 60 canbe rotated whereby the cylindrical member 54 can be removed for cleaningor replacement.

The association of the cylindrical member with the plate 64 permitsadjustment of this member to achieve uniform distribution of developeron to the paper tape. Thus, it will be noted that the plate 64 issecured to the stationary frame member 66 of the apparatus by means ofscrew 28, and 72. The screws 68 and 70 (see FIGURE 3) permit adjustmentof the plate 64 about the bushing 71 whereby the slot 56 can be disposedexactly opposite the lowermost point of the roller 58.

The screw 72 passes through the frame member 66 and is threaded into theplate 64. Movement of this screw tend to pivot the plate 64 whereby thecylindrical member 54 can be swung to locate the slot 56 in a positionin parallel with the surface of the roller 58. This adjustment is alsodesirable in case the pressure of the liquid within the cylindricalmember varies from end to end, and, therefore, the uniformity indistribution of the liquid can be achieved by moving the cylindricalmember somewhat out of parallel with respect to the roller 58. A spring74 is fastened on the plate 64 and this spring engages pin 76 wherebythe plate 64 and the associated cylindrical member 54 will be heldsteady within the apparatus.

A pair of projection members 73 extend outwardly from the frame 66 andclamps 79 connected to the tray 44 engage these projecting members. Bydisconnecting the outlet line 50, the tray 44 can be easily removed forcleaning or replacement.

The drying apparatus 40 illustrated in detail in FIG- URES 6, 7 and 8includes an air inlet duct 80 located at its upper end. A plurality ofguide vanes 82 extend an gularly downwardly from this duct and thesevanes define a plurality of passages each of which terminates in adistributor 84. Outlet openings 86 of these distributors are located ata plurality of vertical levels in the apparatus and these openingscommunicate with the paper tape 24) as it is moved upwardly through thedryer.

A vertical plate 88 is positioned in opposed relationship with respectto the outlet openings 86 and the passage for the tape 29 is definedbetween this plate and the outlet openings. The plate 88 is fastened toa housing 90 and this housing confines heating elements 92. Terminals 94extend through the housing whereby power can be trans mitted to theheating elements and whereby heat can be radiated from the plate 88.Adjusting screws 95 hold the elements 92 against the plate 88.

The distributors 84 include baffles 96 within their interiors. Screws 98are associated With these baffles adjacent the outlet openings 86. Byrotating these screws, the spacing between the members 96 and the upperwall of the distributors 534 can be regulated, and, therefore, thepassage of drying air into contact with the paper tape can becontrolled. Exhaust ducts 1439 are formed adjacent the outlets 86 forremoval of the drying air.

In the operation of the drying apparatus, the paper tape is fed from thedeveloping means 38 to the lower end of the drying apparatus where guiderollers 24 direct the tape upwardly between the plate 88 and the outletopenings S6. The drying air is delivered to the surface of the papertape whereby the liquid developer will be fixed on the surface of thetape in a highly etficient manner. The heating provided by means of theplate 86 will serve to provide a more rapid drying operation and theseheating means are particularly desirable in situations where the amountof developer used, the nature of the paper tape, or atmosphericconditions present a particularly wet tape. In this connection, it isalso contemplated that the drying air be heated to further acceleratethe drying operation. It will be understood, however, that the amount ofheat employed is relatively low and does not approach temperatures whichwould tend to char the paper.

As indicated, the particular drying apparatus is effective to improvethe efficiency of operation in the production of copy material providedby means of a liquid developing system. It is contemplated, however,that the devel' oping system be employed with less efficient dryingmeans including the passage of the tape over guide rollers in theapparatus until it dries without the use of accelerating mechanisms.However, the described drying apparatus is particularly suitable for therapid drying of the tape, under conditions such as high humidity Wherethe tape will not dry of its own accord, and in situations where it isnot desirable to take up undue space for transporting the tape while itdries of its own accord.

In order to provide an efiicient operation for the pro duction of copysheets while using liquid developing techniques, it is important that asuitable liquid developer be employed. Reference is made to copendingapplication Serial No. 205,690, filed June 27, 1962, and entitledComposition and Method for Developing Latent Electrostatic Images, for adisclosure of suitable developers.

It will be understood that various changes and modi fications can bemade in the above described apparatus which provide the characteristicsof this invention without departing from the spirit thereof particularlyas defined in the following claims.

That which is claimed is:

1. An apparatus for developing a latent image produced on a paper tapeby means of an electrostatic technique, said apparatus comprising meansfor continuously moving said tape to a developing means, a source ofliquid developer, and means for drying said tape after application ofthe developer thereto, said developing means comprising a horizontallydisposed enclosure located beneath the path of movement of said tape, anelongated, horizontally disposed slot defined at the top of saidenclosure and extending perpendicular to the direction of movement ofsaid tape, feeding means for continuously supplying liquid developer, atubular member disposed within said enclosure, the length of saidtubular member being substantially coextensive with the length of saidslot, said tubular member communicating with said feeding means, atleast one opening defined by said tubular member whereby liquiddeveloper is adapted to be fed into the tubular member and out of saidopening into said enclosure for distribution onto said tape through saidslot, a guide roller, said guide roller and said enclosure beingmaintained in closely spaced apart relationship whereby said tapecontacts the upper surface of said enclosure and the bottom side of saidroller, and tray means disposed beneath said enclosure for collectingunused developer liquid.

2. An apparatus for developing a latent image produced on a paper tapeby means of an electrostatic technique, comprising means for moving saidtape to a developing means, a source of liquid developer, and means fordrying said tape after application of the developer thereto, saiddeveloping means comprising an enclosure which defines an elongated slotextending perpendicular to the direction of movement of said tape, meansfor feeding said liquid developer into said enclosure whereby it isadapted to pass out through said slot into contact with said tape, saiddeveloping means including a guide roller, and wherein said tape ispassed continuously through said apparatus and into contact with saidroller, the enclosure of said developing means including a cylindricalmember positioned in closely spaced relationship with respect to saidguide roller whereby said tape is adapted to pass between saidcylindrical member and said guide roller, said slot being formed in theupper side of said cylindrical member and said tape passing in contactwith the lower surface of said guide roller, an internal tubular memberin communication with said source of liquid developer, a pair ofopenings defined in the lower side of said tubular member at either endthereof for passing said developer into said cylindrical member, andmeans for continuously supplying said developer whereby the developercontinuously moves out of said slot into contact with said paper tape.

3. An apparatus in accordance with claim 2 including means for adjustingthe position of said enclosure relative to said tape whereby uniformpassage of developer out of said slot into contact with said tape can beachieved.

4. An apparatus for developing a latent image produced on a sheet bymeans of an electrostatic technique, com prising means for moving saidsheet to a developing means, a source of liquid developer, meanspositioned at said developing means for uniformly distributing saiddeveloper over the face of said sheet having said latent image thereon,a drying means including a source of drying air, means for moving saidsheet through said drying means, and means for distributing air over thesurface of said sheet whereby said developer is fixed on said sheet,said drying means comprising a vertically disposed housing, and an airinlet at the top of said housing, a plurality of guide vanes extendingdownwardly from said housing and defining passages to said distributingmeans, said distributing means being located at a plurality of verticallevels in said drying means and means for passing said sheet closelyadjacent the outlet openings of said distributing means.

5. An apparatus in accordance with claim 4 including means for adjustingthe size of said outlet openings to regulate the passage of drying airtherethrough.

6. An apparatus for developing a latent image produced on a paper tapeby means of an electrostatic technique, comprising means for moving saidtape to a developing means, a source of liquid developer, meanspositioned at said developing means for uniformly distributing said dveloper over the face of said tape having said latent image thereon, adrying means comprising a vertically disposed housing, means for movingsaid tape through said drying means, means for supplying drying air tosaid drying means, an air inlet at the top of said housing for receivingsaid air, a plurality of guide vanes extending downwardly from saidhousing and defining passages therebetween, distributing means locatedin communication with each of said passages, means for adjusting thesize of said distributing means to regulate the passage of drying airtherethrough, said distributing means being located at a plurality ofvertical levels in said drying means and means for passing said tapeupwardly through said drying means closely adjacent the outlet openingsof said distributing means.

7. An apparatus in accordance with claim 6 including a vertical platepositioned in opposed relationship with respect to said outlet openingswhereby the path of movement of said paper tape is defined between saidplate and said outlet openings, and including heating means positionedbehind said plate for assisting in the drying of said tape.

References Cited by the Examiner UNITED STATES PATENTS 927,995 7/1909Morrow 34-156 998,206 7/1911 Ross et al 34160 X 1,361,932 12/1920 VanAvermaete 118-410 2,008,230 7/1935 Spooner 34156 X 2,269,169 1/1942 VanDerhoef et al. 118412 X 2,724,907 11/1955 Walter 34160 X 3,012,83912/1961 Epstein et al 118637 X 3,038,073 6/1962 Johnson 118637 X3,058,405 10/1962 Limberger 118637 X 3,096,198 7/1963 Schatfert 1171113,124,484 3/1964 Magnusson 118-259 X 3,168,021 2/1965 Levene 118637 X3,176,653 4/1965 Hansen l18410 X CHARLES A. WILLMUTH, Primary Examiner.WILLIAM D. MARTIN, Examiner.

1. AN APPARATUS FOR DEVELOPING A LATENT IMAGE PRODUCED ON A PAPER TAPE BY MEANS OF AN ELECTROSTATIC TECHNIQUE, SAID APPARATUS COMPRISING MEANS FOR CONTINUOUSLY MOVING SAID TAPE TO A DEVELOPING MEANS, A SOURCE OF LIQUID DEVELOPER, AND MEANS FOR DRYING SAID TAPE AFTER APPLICATION OF THE DEVELOPER THERETO, SAID DEVELOPING MEANS COMPRISING A HORIZONTALLY DISPOSED ENCLOSURE LOCATED BENEATH THE PATH OF MOVEMENT OF SAID TAPE, AN ELONGATED, HORIZONTALLY DISPOSED SLOT DEFINED AT THE TOP OF SAID ENCLOSURE AND EXTENDING PERPENDICULAR TO THE DIRECTION OF MOVEMENT OF SAID TAPE, FEEDING MEANS FOR CONTINUOUSLY SUPPLYING LIQUID DEVELOPER, A TUBULAR MEMBER DISPOSED WITHIN SAID ENCLOUSURE, THE LENGTH OF SAID TUBULAR MEMBER BEING SUBSTANTIALLY COEXTENSIVE WITH THE LENGTH OF SAID SLOT, SAID TUBULAR 